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<H3><A NAME="7_1_8">7.1.8 Using logarithmic scale</A></H3>
<P> Using a logarithmic scale requires you to include the logarithmic
 add on module in &quot;jpgraph_log.php&quot;. So you must have the line<DIV class="phpscript">
<CODE><FONT color="#000000"> <FONT color="#0000BB">&nbsp;</FONT><FONT color="#007700">
include(</FONT><FONT color="#DD0000">&quot;jpgraph_log.php&quot;</FONT><FONT color="#007700">
);</FONT><FONT color="#0000BB"></FONT></FONT></CODE></DIV></P>
<P>on the top of your code. To Illustrate how to use a logarithmic scale
 let's make the right Y scale in the previous example a logarithmic
 scale. This is done by the line<DIV class="phpscript"><CODE><FONT color="#000000">
 <FONT color="#0000BB">&nbsp;$graph</FONT><FONT color="#007700">-&gt;</FONT><FONT
color="#0000BB">SetY2Scale</FONT><FONT color="#007700">(</FONT><FONT color="#DD0000">
&quot;log&quot;</FONT><FONT color="#007700">);</FONT><FONT color="#0000BB"></FONT></FONT>
</CODE></DIV></P>
<P>This will then give the following result<DIV class="example">
<BR> <A href="exframes/frame_example7.html" target="blank"><IMG border="0"
HEIGHT="200"       src="img/img/img/img/img/img/example7.png" WIDTH="350"></A>
<BR><B>Figure 17:</B> Using a logarithmic scale for both the Y2 axis <A href="exframes/frame_example7.html"
target="blank">[src]</A>&nbsp;
<P></P>
</DIV></P>
<P></P>
<P> You can of course also use a logarithmic X-scale as well. The
 following example shows this.<DIV class="example">
<BR> <A href="exframes/frame_loglogex1.html" target="blank"><IMG border="0"
HEIGHT="300"       src="img/img/img/img/img/img/loglogex1.png" WIDTH="500"></A>
<BR><B>Figure 18:</B> Example of using log scale on both X and Y axis
 together with a linear Y2 scale <A href="exframes/frame_loglogex1.html" target="blank">
[src]</A>&nbsp;
<P></P>
</DIV></P>
<P> Even though we have so far only shown line graphs logarithmic scale
 can also be used for bar, error, scatter plots as well. Even radar
 plots supports the use of logarithmic plots. The following example
 shows how to use a logarithmic scale for a bar graph.</P>
<P><DIV class="example">
<BR> <A href="exframes/frame_logbarex1.html" target="blank"><IMG border="0"
HEIGHT="220"       src="img/img/img/img/img/img/logbarex1.png" WIDTH="400"></A>
<BR><B>Figure 19:</B> Example of using logarithmic scale togther with
 bar plots <A href="exframes/frame_logbarex1.html" target="blank">[src]</A>
&nbsp;
<P></P>
</DIV></P>
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